A patient with primary sclerosing cholangitis developed cholangiocarcinoma. Which is the MOST common site of cholangiocarcinoma?

Cholangiocarcinoma (CCC): CCC typically refers to mucin-producing adenocarcinomas (different from HCC) that arise from the bile ducts. They are grouped by their anatomic site of origin, as intrahepatic, hilar (central, 65% of CCCs), and peripheral (or distal, 30% of CCCs). Predisposing diseases, Primary sclerosing cholangitis Liver fluke in Asians, especially Opisthorchis viverrini and Clonorchis sinensis. Also know: Nodular tumors arising at the bifurcation of the common bile duct are called Klatskin tumors and are often associated with a collapsed gallbladder. Ref: Carr B.I. (2012). Chapter 92. Tumors of the Liver and Biliary Tree. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.